/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.message;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

import org.apache.http.Header;
import org.apache.http.HeaderIterator;
import org.apache.http.util.CharArrayBuffer;

/**
 * A class for combining a set of headers. This class allows for multiple
 * headers with the same name and keeps track of the order in which headers were
 * added.
 * 
 * 
 * @since 4.0
 */
public class HeaderGroup implements Cloneable, Serializable {

	private static final long serialVersionUID = 2608834160639271617L;

	/**
	 * The list of headers for this group, in the order in which they were added
	 */
	@SuppressWarnings("rawtypes")
	private final List headers;

	/**
	 * Constructor for HeaderGroup.
	 */
	@SuppressWarnings("rawtypes")
	public HeaderGroup() {
		this.headers = new ArrayList(16);
	}

	/**
	 * Removes any contained headers.
	 */
	public void clear() {
		headers.clear();
	}

	/**
	 * Adds the given header to the group. The order in which this header was
	 * added is preserved.
	 * 
	 * @param header
	 *            the header to add
	 */
	@SuppressWarnings("unchecked")
	public void addHeader(Header header) {
		if (header == null) {
			return;
		}
		headers.add(header);
	}

	/**
	 * Removes the given header.
	 * 
	 * @param header
	 *            the header to remove
	 */
	public void removeHeader(Header header) {
		if (header == null) {
			return;
		}
		headers.remove(header);
	}

	/**
	 * Replaces the first occurence of the header with the same name. If no
	 * header with the same name is found the given header is added to the end
	 * of the list.
	 * 
	 * @param header
	 *            the new header that should replace the first header with the
	 *            same name if present in the list.
	 */
	@SuppressWarnings("unchecked")
	public void updateHeader(Header header) {
		if (header == null) {
			return;
		}
		for (int i = 0; i < this.headers.size(); i++) {
			Header current = (Header) this.headers.get(i);
			if (current.getName().equalsIgnoreCase(header.getName())) {
				this.headers.set(i, header);
				return;
			}
		}
		this.headers.add(header);
	}

	/**
	 * Sets all of the headers contained within this group overriding any
	 * existing headers. The headers are added in the order in which they appear
	 * in the array.
	 * 
	 * @param headers
	 *            the headers to set
	 */
	@SuppressWarnings("unchecked")
	public void setHeaders(Header[] headers) {
		clear();
		if (headers == null) {
			return;
		}
		for (int i = 0; i < headers.length; i++) {
			this.headers.add(headers[i]);
		}
	}

	/**
	 * Gets a header representing all of the header values with the given name.
	 * If more that one header with the given name exists the values will be
	 * combined with a "," as per RFC 2616.
	 * 
	 * <p>
	 * Header name comparison is case insensitive.
	 * 
	 * @param name
	 *            the name of the header(s) to get
	 * @return a header with a condensed value or <code>null</code> if no
	 *         headers by the given name are present
	 */
	public Header getCondensedHeader(String name) {
		Header[] headers = getHeaders(name);

		if (headers.length == 0) {
			return null;
		} else if (headers.length == 1) {
			return headers[0];
		} else {
			CharArrayBuffer valueBuffer = new CharArrayBuffer(128);
			valueBuffer.append(headers[0].getValue());
			for (int i = 1; i < headers.length; i++) {
				valueBuffer.append(", ");
				valueBuffer.append(headers[i].getValue());
			}

			return new BasicHeader(name.toLowerCase(Locale.ENGLISH),
					valueBuffer.toString());
		}
	}

	/**
	 * Gets all of the headers with the given name. The returned array maintains
	 * the relative order in which the headers were added.
	 * 
	 * <p>
	 * Header name comparison is case insensitive.
	 * 
	 * @param name
	 *            the name of the header(s) to get
	 * 
	 * @return an array of length >= 0
	 */
	@SuppressWarnings("unchecked")
	public Header[] getHeaders(String name) {
		@SuppressWarnings("rawtypes")
		ArrayList headersFound = new ArrayList();

		for (int i = 0; i < headers.size(); i++) {
			Header header = (Header) headers.get(i);
			if (header.getName().equalsIgnoreCase(name)) {
				headersFound.add(header);
			}
		}

		return (Header[]) headersFound.toArray(new Header[headersFound.size()]);
	}

	/**
	 * Gets the first header with the given name.
	 * 
	 * <p>
	 * Header name comparison is case insensitive.
	 * 
	 * @param name
	 *            the name of the header to get
	 * @return the first header or <code>null</code>
	 */
	public Header getFirstHeader(String name) {
		for (int i = 0; i < headers.size(); i++) {
			Header header = (Header) headers.get(i);
			if (header.getName().equalsIgnoreCase(name)) {
				return header;
			}
		}
		return null;
	}

	/**
	 * Gets the last header with the given name.
	 * 
	 * <p>
	 * Header name comparison is case insensitive.
	 * 
	 * @param name
	 *            the name of the header to get
	 * @return the last header or <code>null</code>
	 */
	public Header getLastHeader(String name) {
		// start at the end of the list and work backwards
		for (int i = headers.size() - 1; i >= 0; i--) {
			Header header = (Header) headers.get(i);
			if (header.getName().equalsIgnoreCase(name)) {
				return header;
			}
		}

		return null;
	}

	/**
	 * Gets all of the headers contained within this group.
	 * 
	 * @return an array of length >= 0
	 */
	@SuppressWarnings("unchecked")
	public Header[] getAllHeaders() {
		return (Header[]) headers.toArray(new Header[headers.size()]);
	}

	/**
	 * Tests if headers with the given name are contained within this group.
	 * 
	 * <p>
	 * Header name comparison is case insensitive.
	 * 
	 * @param name
	 *            the header name to test for
	 * @return <code>true</code> if at least one header with the name is
	 *         contained, <code>false</code> otherwise
	 */
	public boolean containsHeader(String name) {
		for (int i = 0; i < headers.size(); i++) {
			Header header = (Header) headers.get(i);
			if (header.getName().equalsIgnoreCase(name)) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Returns an iterator over this group of headers.
	 * 
	 * @return iterator over this group of headers.
	 * 
	 * @since 4.0
	 */
	public HeaderIterator iterator() {
		return new BasicListHeaderIterator(this.headers, null);
	}

	/**
	 * Returns an iterator over the headers with a given name in this group.
	 * 
	 * @param name
	 *            the name of the headers over which to iterate, or
	 *            <code>null</code> for all headers
	 * 
	 * @return iterator over some headers in this group.
	 * 
	 * @since 4.0
	 */
	public HeaderIterator iterator(final String name) {
		return new BasicListHeaderIterator(this.headers, name);
	}

	/**
	 * Returns a copy of this object
	 * 
	 * @return copy of this object
	 * 
	 * @since 4.0
	 */
	@SuppressWarnings("unchecked")
	public HeaderGroup copy() {
		HeaderGroup clone = new HeaderGroup();
		clone.headers.addAll(this.headers);
		return clone;
	}

	@SuppressWarnings("unchecked")
	@Override
	public Object clone() throws CloneNotSupportedException {
		HeaderGroup clone = (HeaderGroup) super.clone();
		clone.headers.clear();
		clone.headers.addAll(this.headers);
		return clone;
	}

	@Override
	public String toString() {
		return this.headers.toString();
	}

}
